Taking the Temperature of Earth's Core

By duplicating the extreme heat and pressure at the Earth’s core, a European research team has determined that the temperature of the center of our planet is close to 11,000 degrees Fahrenheit — nearly 2,000 degrees hotter than previously thought.

Earth’s solid inner core is surrounded by a fluid outer core, with the boundary between the two expected to be the temperature of the melting point of highly pressurized iron — the primary ingredient of both layers. Researchers placed a speck of iron between two small conical diamonds and applied laser-beam heat and 200 gigapascals of pressure. As the iron changed from solid to molten, they measured the temperature by noting a change in how X-rays were diffracted — a faster, more precise method than the simple visual techniques used in older experiments.

To mimic conditions at Earth’s Core, scientists cranked up the heat and pressure, then used synchrotron X-rays to gauge when iron turned from solid to liquid.

ESRF/Denis Andrault

Knowing Earth’s core temperature is key to understanding the planet’s internal processes, particularly its magnetic field and geothermal activity, explains research team leader Simone Anzellini of the French Alternative Energies and Atomic Energy Commission.